I wonder: Where these guys go at night?

[San Francisco]  I came upon this man and his pets on O'Farrell Street at Powell earlier this afternoon.  It's hard not to notice a man with a white rat that is perched on top of a big tabby cat that itself is laying on top of a dog.

It was hard for this young man to pass the quartet by without asking if he could pet the rat.

I'm feeling a bit sheepish that I neither asked if I could take a photo, nor did I drop something in his collection can.  I was to amazed that he was sitting there with these three animals, all getting along. 

There's a lesson in there somewhere.